One of the things that causes problems for the registry of a computer is temporary files that are stored in that area. When programs or email attachments are downloaded, sometimes there are temporary files that are sent to the registry and they end up staying there. Over time, these can build up and cause the computer to slow down or even crash. There are many registry cleaner programs available to purchase, but the best registry cleaner for Vista is one that is compatible with the new operating system. Not all programs work with Vista, so one that does is crucial. You also want to find one that will find errors and fix them quickly.